The present invention relates to a heat engine, more particularly to a heat engine in which a power generating apparatus is placed and operates in the exhaust gas of topping cycle, and compressor/combustor/turbine of a gas turbine and turbine/cooler/compressor of the power generating apparatus are operated simultaneously in such a manner that their permutations of components are opposite as if a mirror surface was virtually set between both cycles.
Users of gas turbines have spread in many other sectors than aeroengines originally used, which include land industries, marines, vehicles and electric power generation in recent years, and their improvements in thermal efficiency and simplification of the structure have been carried out.
In order to raise the thermal efficiency of industrial gas turbines, there are two main systems. One is a xe2x80x9ccombined cyclexe2x80x9d that passes water through the exhaust gas of gas turbines to generate steam for a steam turbine, and to increase outputs. The other is a xe2x80x9cregeneration cyclexe2x80x9d that returns an amount of exhaust heat energy to an outlet of the compressor of gas turbines to increase an air temperature in front of combustor and then to reduce input fuel. The combined cycle is used in the large-sized gas turbines such as a power plant, and the regeneration cycle is mainly used in the medium and small-sized gas turbines.
Moreover, since natural gas, which has been largely started to use recently, is carried in at cryogenic liquid state by ship from abroad in Japan, it must be vaporized in order to use it as fuel. At present, such vaporization is carried out by use of sea water. However, since temperature of sea water drops several degrees, the sea water must be heated up to the original temperature and then returned to the sea in consideration of influence on the ecosystem. There may be sometimes a case that an LNG cryogenic power generation of Rankine cycle is employed by using the difference in temperature between sea water and liquid natural gas, which is about 180 degrees.
The above-described combined cycle system, that is, the system using both of a gas turbine and a steam turbine, which is widely used in the power plant, becomes established worldwide as an effective system for increasing overall thermal efficiency. However, the combined cycle system needs large-sized facilities including a boiler with considerable costs attendants particulary for steam turbines. Moreover, the combined cycle cannot be always operated at an optimum pressure ratio because of the limited temperature of the metallic surface of the boiler that generates steam.
On the other hand, the regeneration cycle system, which is used to improve the thermal efficiency of the medium and small-sized gas turbines, requires a heat exchanger resisting high temperature in the exhaust gas, where the temperature difference to be used for the heat exchange is low, so that high exchange temperature efficiency cannot be expected. Furthermore, in the system where a compression ratio of gas turbines increases, it becomes very difficult to have an efficient heat exchange.
The present invention can be applied to a natural gas manufacture. In the conventional liquid natural gas manufacturing technique, the LNG cryogenic power generation, which uses the temperature difference of about 180 degrees between sea water and liquid gas, so as to generate power by Rankine cycle by use of chlorofluorocarbon, has been tried. However, in the conventional technique, since power generation efficiency is low by a few percent and chlorofluorocarbon is used as a working medium, this system is on the decline.
One object of the present invention is to eliminate the drawback of the above-mentioned system to improve the thermal efficiency of gas turbines. In addition, another object of the present invention is to carry out natural gas manufacturing and power generation simultaneously at higher efficiency than ever made.
The other object of the present invention is to provide a heat engine wherein thermal efficiency is increased by mainly using the known components whose manufacturing method is established and newly combining the respective components, and to contribute to carbon dioxide reduction effect around the world.
The heat engine of the present invention is characterized by that a power generating apparatus, which makes high temperature gas of normal pressure or pressure close to normal pressure to flow into a turbine, and then performs heat exchange to lower temperature of gas in front of an inter cooled compressor, is placed and operated in the ehaust gas of topping cycle, and compressor/combustor/turbine of a gas turbine and turbine/cooler/compressor of the power generating apparatus are operated simultaneously in such a manner that their permutations of components are opposite as if a mirror surface was set virtually between both cycles. The power generating apparatus of the present invention is of the heat engine that actuates by two cycles reflected on a mirror surface, and works as a bottoming cycle of expansion/cooling/compression, which are opposite to the processes of compression/heating/expansion performed by the normal gas turbines.
In addition, the present invention can be used in place of the combined cycle with a large-sized steam turbine or the regeneration cycle of the medium and small-sized gas turbines which is generally used for general industries or vehicles. Moreover, the application of cooling in the present invention to the liquid natural gas manufacturing makes it possible to realize gasification and power generation simultaneously.
According to the first solving means of the present invention, a heat engine is provided which comprises:
a gas turbine having a first compressor, a combustor, and a first turbine; and
a power generating apparatus having:
a second turbine attached to the back portion of exhaust gas of said gas turbine , and said second turbine into which high-temperature exhaust gas is made to flow from said first turbine at normal pressure or pressure close to the normal pressure;
a cooler into which exhaust gas is made to flow from said second turbine to perform heat exchange, whereby reducing the temperature of exhaust gas;
a second compressor into which exhaust gas is made to flow from said cooler; and
an inter cooled portion into which exhaust gas is made to flow from said second compressor to perform heat exchange.
Moreover, according to the present invention, the intercooling section of the power generating apparatus comprises an intercooler into which exhaust gas is made to flow in the second compressor to perform heat exchange for reducing the temperature of gas, and one or a plurality of intercoolers having inter compressor into which exhaust gas is made to flow from the intercooler.